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I used Paypal and it didn't give me the option to use the credit card for currency conversion. Paypal did the currency conversion.
This is not legal under the Paypal terms and conditions. So I've been overcharged.
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Finally, got a proper answer out of Paypal. It's a process that's made to get you to give up. I had to edit their steps as they got it wrong.

True that Paypal exchange rates are poor compared to credit card exchange rates BUT remember all credit cards have a 3% fee (often hidden) when used to buy goods/services in a foreign currency. Does Paypal charge a conversion fee on top of the exchange rate?

There are ways for Aussies to effectively avoid paying the GST; I will not go into too many details here but Aussie club members firstly should gather together (to save on shipping by combining orders) and have their USA contact buy the items from a USA supplier then resend the items (stripped of their packaging) to Australia. What happens to the value of say a new Stipe shock when it's removed from it's factory packaging then wrapped in newspaper???

USA suppliers when sending stuff to Australia don't do a huge amount of investigation into what's the cheapest way. The cheapest way varies depending on the weight and dimensions of the package. There are many options to look at such as USPS International flat rate boxes (max. weight 20 pounds).

Example: Two Aussie A club members decide they want 4 Stipe shocks each and are smart enough to decide to buy the items together to save on shipping.

8 Stipe shocks = approx. USD 2000 + shipping to Oz

When the package arrives in Australia they'll need to play the equivalent of USD 200+ in AUD to be given the package. No way to avoid this as the seller has declared the sale price on the package (or included the invoice). On top of that, USA suppliers do not often choose cheapest way to send items to Australia plus they do not take care to keep packaging to a minimum so the total weight doesn't exceed thresholds; even one gram over a certain threshold can mean USD 50 or more added to shipping. And remember the 10% GST is also charged on the shipping amount.

The problem with these schemes to avoid the tax is that both the buyer and seller might be charged with avoiding tax, a Federal Offense. That said, buying through a US entity would overcome the refusal by some US companies to ship to Australia. For an Australian to do this himself, he would likely need a US bank account. With the closed US system, opening one isnít easy and would at least require a trip to the US. That represents more $
I have used a freight consolidator to ship stufff here by surface freight. It takes a few weeks but it isnít hard to plan that far ahead, besides, the local guy has just about everything available in the US and some that are not.
This could be a bonanza for him.

My son and I were looking at that last evening after I told him about reading this thread. He had just sold some parts to Australia on eBay and the customer was charged the extra 10 per cent but it was not put into my son's paypal account so we assume eBay is charging and paying it to Australia.